Method for preparing alkylidenesuccinic esters



Patented Feb. 21, 1950 METHOD FOR PREPARING ALKYLIDENE- SUCCINIC ESTERSMilton 0. Kloetzel, Los Angeles, Calif., assignor to Commercial SolventsCorporation, Terre Haute, Ind., a corporation of Maryland No Drawing.

Application December 18, 1947, Serial No. 792,602

6 Claims. (01. 260-485) My invention relates to a new and useful processfor the production of alkylidenesuccinic esters having the followingstructural formula:

in which R represents a lower alkyl radical, and

R and R are selected from the groupconsisting ethylidenesuccinate,diethyl n-propylidenesuc.

cinate and diethyl teraconate.

Prior investigators in this field found that primar and secondarynitroalkanes would add to alpha, beta-unsaturated carbonyl compounds bymeans of the action of sodium amide, sodium alkoxides and other stronglybasic materials. I have attempted the same reaction using a secondaryamine such as diethylamine, but with entirely surprising results. I havefound that if one mole of ester is employed to three moles ofnitroalkanes and two-tenths of a mole of diethylamine, it is possible toobtain a good yield of nitro ester. However, if one mole of ester isused to three moles of nitroalkanes and at least one mole ofdialkylamine, the reaction product is not a nitro ester but rather, analkylidenesuccinic ester. This unusual product may be explained by theloss of the elements of nitrous acid from the originally formednitroester.

The preparation of either the nitroesters or the alkylidenesuccinicesters by the above described method is preferably effected attemperatures of about 20-30 C.

The esters which may be employed in my new process are represented bythe following formula:

ire-Conn R1O:C--CH wherein R represents a lower alkyl group (i. e.having 6 or less carbon atoms). As examples of such esters, there may bementioned 'dimethyl fumarate, diethyl fumarate, dimethyl maleate, anddiethyl maleate. When maleic esters are used in this process they firstrearrange to the respective fumaric acid esters in the presence of thesecondary amine catalyst.

The nitroalkanes which are operative in my process may be represented bythe following formula:

11 NOi wherein R and R are selected from the group consisting ofhydrogen and alkyl groups. Nitroalkanes typical of this class includenitromethane, nitroethane, 2-nitropropane, l-nitropropane, 2-nitrobutane, l-nitrobutane. Z-nitropentane, and the like. I 1

The'examples which follow are illustrative of the procedures-by whichalkylidenesuccinic esters may be synthesized by my new process. It is tobe specifically understood, however, that these examples in no way limitthe scope of my invention, since I have found that the reaction involvedis very general in nature, and will occur, under the conditionsdescribed in the reaction of substantially any primary or secondarynitroalkanes with an alkyl ester of fumaric or maleic ester under theinfluence of the secondary amine used.

EXAMPLE I A mixture of dimethyl or diethyl fumarate (1 mole), thenitroalkane (3 moles) and diethylquentl until all of the ester haddissolved (several hours). In most instances the mixturebecame warm fromheat of reaction.

After standing for an appropriate period (se Table I) the coloredsolution (orange to red) was subjected to reduced pressure distillation(40 C. at 12 mm.) to remove diethylamine, nitroalkane and water.Fractionation of the residue, employing a ten-inch Vigreux column,yielded yellow N- nitrosodiethylamine (B. P. '72-'75 C. at 12 mm.)followed by the higher-boiling alkylidenesuccinic ester. Removal oftraces of basic impurities from the esters was effected by extractionwith 10% hydrochloric acid. A final vacuum distillation yielded pureproducts with properties shown in Table I.

The N-nitrosodiethylamine produced in these reactions was identified byconversion to diethylammonium chloride by means of anhydrous hydrogenchloride. The chloride separated from anhydrous ethanol-ether in large,colorless, transparent plates; M. P. 222-223" C.

This general; reaction was used to prepare the compounds listed in TableI.

TABLE I Alkylz'denesuccinic esters from condensation of nitroalkane (3moles)v with fumarates (1 mole) at 30 in presence of diethylamine (1-1.1moles) Reaction :1

Fumarate -N1troalkane Product 7 111313;: g gg d1:

Dimethyl Nitromethanenfl. Dimethyl itaconato 5 1 22-43 56-58/1. 2 1.4457 1. 1246 Do. Nitroethane Dimethyl ethylidenu-suceinate. 6 77 7374/1.5 1. 4553 1. 1058 Do. l-Nitropropane. Dirnethyln-propylidene-succinete.. 14 86 78.5-80/1. 25 1. 4555 1. 0746 .Do...2-Nitropropane .-j .Dimethyl teraconatej .143 3 85 77-78/1. 5 1. 4581 1.0788 Diethyl Nitromethaneufl; Diethyl itaconate- 11 45 68-69/1. 25 4 l.4398 1. 0459 'Do Nitroethane Diethjl ethy1ic1ene-suecinate 11 88 82/1.25 1. 4484 1. 0437 Do 1-Nitro' propane Diethyl n-propyIidene-succinat1'0 95 88-90/1. 25 1. 4491 1.0171 Do 2-Nitropr'opan'e Diethylter-aconate. I8 83 87/1. 25 1. 4537 1. 0261 1 Viscous polymer of theitaconateailso obtained, thereby amountingrfortheilowyiifl of pureester.

'Knops, Ann, 248 200 (1888) reported 1.444125.

3 There was also obtained 211%.oimethylfi(l=.nitrois%rnzopyl)-fsuceinate 1B. 1B. 135 18? at 2.5 mm.

v Knops, Ann., 248, 201 (1888) reported no 1.4387. Thealkylidenesuccinic esters of my invention are useful'as intermediates inthe preparation of numerous organic compounds. Other uses ofthese-products will readily occur to those skilled in the art.

Now having described my invention, what I claim is:

1. In the process for the preparation of alkylidenesuccinic esters ofthe formula V wherein R "represents a lower alkyl radical, R

wherein R "represents a lower alkyl radical, and

a nitroalkane of the formula wherein R and R are selected from the.group consisting of hydrogen and. 'alkyl groups, by means ofa'dialkylamine, said d ial'lkyi amine being used in-the proportion 'o-fat "least one mole per mole of ester and three moles of nitroalkane.

2; The process of xilaim 1 wherein .one mole of the ester is reactedwith 'three males of the nitroalkane in the presence of :at least onemole of dialkylamine,

3. The process of claim 1 wherein the amine is ti'iethylamine.

4. In a, process for t -e preparation of dimethyl npropyl'rdene'succinate, the step which'eomprises causing dimethyl'fu-m'arate and "l-nitropropane,

in the proportion of one "mole of dirrre'thyl furnarate to three molesof l-nitropropane, to react in the presence of atleast one mole ofdiethylamine at a temperature of about 20-30 C.

5. In a process for the preparation of dimethyl teraeonate, the stepwhich comprises .eausing dimethy-l maleate and 2 -nitropro pane, in :the,proportion of one mole of dimethyl maleate to three moles ofz-nitropropane, :to react in the presence of (3,1) least one moleof.diethylamine at a temperature of about 20 -30 *0.

ii. In a process or the preparation :of diethyl ethyli'denesuceinajte.the step which comprises causing diethyl .fumarate and .nitroeth-ane,.in the proportion of one mole of diethyl ifumarate to three :moles ofnitreethane, to :react in the presence of at least one mole of=d-iethy1amine at a temperature of about 20 -230 C.

REFERENCES CI'TED The foliowing'mefierences are :of record in the fileof this patent:

UNITED S71ZATES'BATENTS

1. IN THE PROCESS FOR THE PREPARATION OF ALKYLIDENESUCCINIC ESTERS OFTHE FORMULA